Power driven positioning apparatus with force dependent shut-off, to position an engagement element against an abutment

ABSTRACT

A housing, preferably separable into shells encloses a generally U-shaped leaf spring, having projecting legs extending into the housing. A spindle passes through the projecting legs, the spindle being motor driven and connected by threads with the engagement element to provide axial movement of the engagement element upon rotation of the spindle. The spindle is guided in the housing by a sleeve formed in the housing which surrounds axially movable bearings. The bearings are held in axial position by the leg portions of the U-shaped spring, but following axial excursion of the spindle, if the engagement element connected thereto strikes an abutment, causing deflection of the leaf spring and operation of electrical switches as the leg portions of the leaf springs deflect.

United States Patent Balz [451 Nov. 21, 1972 [72] Inventor: JiirgenBiilz, Heilbronn, Neckar,

Germany [73] Assignee: Firma Helmut Balz GmbH, Heilbronn, Neckar,Germany 22 Filed: Nov. 19, 1971 21] Appl.No.:200,453

[30] Foreign Application Priority Data 2,407,537 9/1946 Chapman..192/150 Baumann ..251/134 X Denkowski ..l92/ 150 PrimaryExaminerl3emard A. Gilheany Assistant Examiner-Thomas LangerAtt0mey-Flynn & Frishauf [57] ABSTRACT A housing, preferably separableinto shells encloses a generally U-shaped leaf spring, having projectinglegs extending into the housing. A spindle passes through the projectinglegs, the spindle being motor driven and connected by threads with theengagement element to provide axial movement of the engagement elementupon rotation of the spindle. The spindle is guided in the housing by asleeve formed in the housing which surrounds axially movable bearings.The bearings are held in axial position by the leg portions of the U-shaped spring, but following axial excursion of the spindle, if theengagement element connected thereto strikes an abutment, causingdeflection of the leaf spring and operation of electrical switches asthe leg portions of the leaf springs deflect.

10 Claims, 3 Drawing Figures PATENTEDIIBVZI I972 SHEET 2 OF 2 AQIIGwPOWER DRIVEN POSITIONING APPARATUS WITII FORCE DEPENDENT SHUT-OFF, TOPOSITION AN ENGAGEMENT ELEMENT AGAINST AN ABUTMENT CROSS REFERENCE TORELATED APPLICATIONS AND PATENTS U.S. Patent 3,616,884; U.S. Serial56,608; U.S. Serial 106,030 filed January 13, 1971; U.S. Serial 200,549filed November 19,1971. 7

The present invention relates to a power driven positioning apparatus,and more particularly to such an apparatus in which an engagementelement is pressed with a predetermined force against an abutment, theforce being discontinued when the engagement element strikes theabutment. Such apparatus is used, for example, in connection with thepositioning of valve elements in valve seats. I

Positioning apparatus in which the final positioning force ispredetermined have previously been described, see, for example, thecross referenced patents and applications. In accordance with one of thepreviously disclosed embodiments of such positioning drives, a generallyU-shaped leaf spring is provided, having projecting legs. Ball bearingsare located at the outside of the legs of the leaf spring, the ballbearings being retained in axial position in the housing, with respectto a rotating spindle, by the leg portions of the leaf spring. If thespindle strikes an abutment, it will be subject to axial excursion,carrying along one of the ball bearings (or permitting a ball bearing tobe spring-pressed to move in axial direction). Operating elements, forexample located between the leaf spring, are then located in thehousing, the operating elements engaging electrical switches to shut offelectrical current to a motor driving the spindle. In one construction,a sleeve is located between the legs of the U-shaped-spring, having anaxial dimension which is just slightly less than the distance betweenthe legs of the spring, the sleeve being formed with cam surfaces tooperate electrical switches. Such a construction is shown in detailinthe cross referenced patent application Ser. No. 200,549.

Positioning drives as described are reliable and can be simplyconstructed. Under some conditions, however, the axial loading of thewalls of the housing which retain the bearings joumalling the spindle isundesired, since the housing thus must bemade larger or stronger toaccept this axial loading.

It is an object of the present invention to provide a positioning drive,particularly adapted for valves or the like, which is simple inconstruction, and in which the housing can be made easily and doesnotrequire a strong structure capable of accepting substantial counterforces.

SUBJECT MATTER OF THE INVENTION Briefly, a housing is provided throughwhich a spindle passes, the spindle being motor driven. In a preferredform, the motor is held in the housing by being form-fitted, orfrictionally engaged therein. The housing is preferably made ofseparable shell parts. A U-shaped spring is located in the housing, thelegs of the spring extending towards the spindle, and the spindlepassing therethrough transversely to the legs. The housing is formedwith a guide surrounding the spindle, the bearings being interposedbetween the spindle and the guide in the housing. The bearings are soarranged that they are axially movable with the spindle (for example byforming a groove in the spindle, locating balls on the groove andforming the bearings with races having shoulders thereon, engaged by theballs) so that, when the spindle is subject to axial excursion, forexample when a valve element meets a valve seat, a bearing portion willbe carried along against the force of the legs of the leaf spring andwill move axially. This will cause deflection of the legs of the leafspring, against the resiliency of the spring itself. This deflectingmovement is used to operate a micro switch, or the like,

located between the legs of the leaf spring.

By locating the ball hearings in a sleeve or socket element formed onthe housing and extending between the legs of the leaf spring, it isunnecessary to provide transverse separating walls, or other holders forthe bearings which are sufficiently strong to accept the counter force,generated by the positioning force of the engagement element strikingthe abutment, such as a valve engaging the valve seat.

The construction can be particularly simplified if a pair of shut-offswitches are located between the legs of the leaf spring, the shut-offswitches having operating elements, such as buttons, directly operatedby deflection of the leaf spring. The socket, or sleeve holding thebearings within the housing is preferably provided with internal ribs inorder to prevent rotation of the outer bearing race within the housing,while permitting axial displacement thereof.

Under normal operating conditions, that is, when the positioned elementtravels between extreme positions, the spindle is axially unloaded andthe outer races of the ball bearings are resiliently compressed towardseach other by the leaf spring. The base, or bend of the U-shaped leafspring is preferably directly secured in the housing wall.

It is sometimes desired to provide different movements from a spindle,such as axial movement to position a valve and, in addition, or insteadthereof, rotary movement, for example to shift simultaneously withchanging of the position of a valve member, the position of a throttleor choke. The present invention permits ready adaptation'of suchadditional positioning member by forming a portion of the axially movingexcursion element with rack teeth, and placing a shaft, carrying apinion adjacent the rack teeth, the pinion engaging the rack teeththemselves for rotary motion upon axial displacement of the displacementelement. To prevent deflection of the displacement element against theengagement force of the pinion teeth, a counter, or back-up roller ispreferably provided.

The invention will be described by way of example with reference to theaccompanying drawings, wherein:

FIG. I is a longitudinal sectional view of the positioning apparatus;

FIG. 2 is a transverse sectional view along lines C-D of FIG. 1; and

FIG. 3 is a fragmentary partial view along lines A-B, to an enlargedscale and rotated by with respect to FIG. 1.

A shaft or rod member 1 is held against rotation by means (not shown)and well known in the art, adapted to engage an abutment 1'. The upperend of rod 1 is tapped and threaded, axial movement of rod 1 beingobtained by rotation of a threaded spindle 3 engaging threads 2 withinthe upper end of rod 1. Spindle 3 is rotatably driven by a gear 4,engaging a pinion 5, driven by an electric motor 6.

Spindle 3 is guided for rotation, and axial position by an enlargedcylindrical portion 7, forming also the inner race of a pair of ballbearings 8, 9. Balls 8 are guided axially ingrooves 8' formed inenlarged portion 7 on the spindle; the outer races for the balls 8 areformed by ball bearing shells 9, having shoulders 9a, 9b and axiallybearing from the bottom, and from the top against the circumference ofthe balls 8. The outer races 9 are located in a cylindrical bore of abearing socket or sleeve 10. Bearing socket 10 forms part of housing 11.Housing 11, itself, is formed as a pair of shells 11a, 11b (FIG. 2)suitably secured together (for example by bolts, not shown, flanges, orthe like) and having a separating plane passing through the center ofrod 1, and thus also of spindle 3. The housing shells or halves 11a, 11bare so shaped that the electric motor 6 is retained within the housingshells by interfitting engagement therein, for example by beingfrictionally held, or press-fitted. The bearing socket 10 is also formedof two parts, one each being secured to one of the half shells 11a, 11bof the housing 11, each one having a semi-cylindrical inner form sothat, when the housing halves are fitted together, a cylindrical borewill result, in which the two ballbearing races 9 can be v located.

A generally U-shaped leaf spring has projecting legs 12, 13, extendingabout the bearing socket 10. The two legs l2, 13 are interconnected by abend, or base portion 14 of the spring, the base portion 14 bearing onthe inside against a wall 15 of the housing 11. The bearing socket 10 isformed with ribs 70, 80, against which the legs l2, 13 can bear andwhich further fix the outer surfaces 9a, 9b of the ball bearing races 9in axial direction (FIG. 3). I

A pair of final positioning switches l6, 17, having operating elements16a, 17a, respectively, are located between the legs 12, 13 of the leafspring. The operating elements may be buttons or the like, and form partof the shut-off mechanism, being electrically connected to the'motor 6,or other control equipment.

OPERATION Let it be assumed that rod 1 is part of a valve element, andreaches the final, terminal position. The terminal position will dependon the direction of rotation of spindle 3, causing rod 1 to be screwedin, or out of the spindle. Upon reaching of a terminal position, anaxial excursion of the spindle 3 will result. The balls 8, runningwithin grooves 8' of the portion 7 on the spindle will be subject toaxial excursion, and carry along the outer race 9, due to engagement ofthe ball 8 with r the inner shoulder of the outer race of the ballbearings.

Axial movement of the outer race of the ball bearing causes spreading ofthe leg portions of the leaf spring, against the resilient force of theleaf spring, and operation of the associated switch 16, or 17, effectingelectrical control function, for example shut-off of motor 6.

From time to time it is desired to provide, in addition to a finalpositioning in axial direction, a drive which provides rotary motionover a limited extent. This is desired, for example, when valves are tobe controlled tooperate flaps, chokes, vanes, or the like. Additionaloperation can be obtained by forming a portion of rod 1 as a rack 18,which is engaged by a pinion l9, rotatably held on a shaft 20 which, inturn, is joumalled in housing 1 1 (FIG. 2). Rotation of shaft 20 thus iscoupled to translatory motion of rod 1. To prevent bending of rod 1 dueto transfer of torque transferred between the pinion l9 and rack 18,the'side of the rod 1 opposite the rack surface 18 is supported by acounter or back-up roller 21, engaging a flatsurface 22 formed on rod 1(FIG. 2). 7

Various changes and modifications may be made within the inventiveconcept.

I claim:

1. Power driven positioning apparatus with force-dependent shut-off, toposition an engagement member (1) against an abutment (1') comprising ahousing (15); a

a spindle (3) passing through the housing and adapted to be connected tothe element to be positioned with predetermined force against theabutment;

a motor (6) in driving engagement (4, 5) with the spindle (3), thespindle being subject to axial excursion when the element impinges onthe abutment; 7

bearing means (8, 9) axially spaced on the spindle and joumalling thespindle, the bearing means being axially movable with the spindle uponaxial excursion thereof;

means (10) located in the housing guiding the axial movement of thebearing means;

spring means (12, 13, 14) having projecting portions (12, 13) and anattachment portion (14), the projecting portions extending over thebearing means and holding said bearing means between the projectingportions in pre-determined axial position, the attachment portion beingsecured to the housing;

and switch means (16, 17) engageable by the projecting portions of thespring means upon deflection of the spring means due to engagement ofthe bearing means with the projecting portions of the spring means uponaxial excursion of the spindle.

2. Apparatus according to claim 1, wherein the switch means comprises apair of electrical switches (16, 17) having respective operatingelements (16a, 17a) each, located in the housing for engagement of theoperating elements by the projecting portions of the spring means.

3. Apparatus according to claim 1, wherein the guide means guiding thebearing means are slightly shorter than the distance between theprojecting portions of the spring means.

4. Apparatus according to claim 3, wherein the bearing means comprisesstationary and rotary races, and the spring means locate the stationaryraces in axial position with respect to the spindle within the housing.

5. Apparatus according to claim 3, wherein the hearing means are ballbearing means and comprise grooves formed in the spindle, balls runningin the grooves, and outer races carried along in axial direction uponaxial excursion of the spindle, and hence the balls in the grooves ofthe spindle, said outer races being resiliently compressed against eachother by the projecting portions of the spring means.

shaped leaf spring.

9. Apparatus according to claim 1, wherein the engagement means (1) isnon-rotatable and subject to axial travel upon rotation of the spindle(3), said engagement element being formed with a rack surface; and apinion (l9) engaging the rack surface.

10. Apparatus according to claim 9, including a pinion shaft (20)securing the pinion (19) in position for engagement with the racksurface;

and a counter roller (21) located to bear against the backside of therack surface and prevent deflection of the rack surface away from thepinion shaft.

1. Power driven positioning apparatus with force-dependent shutoff, toposition an engagement member (1) against an abutment (1'') comprising ahousing (15); a spindle (3) passing through the housing and adapted tobe connected to the element to be positioned with predetermined forceagainst the abutment; a motor (6) in driving engagement (4, 5) with thespindle (3), the spindle being subject to axial excursion when theelement impinges on the abutment; bearing means (8, 9) axially spaced onthe spindle and journalling the spindle, the bearing means being axiallymovable with the spindle upon axial excursion thereof; means (10)located in the housing guiding the axial movement of the bearing means;spring means (12, 13, 14) having projecting portions (12, 13) and anattachment portion (14), the projecting portions extending over thebearing means and holding said bearing means between the projectingportions in pre-determined axial position, the attachment portion beingsecured to the housing; and switch means (16, 17) engageable by theprojecting portions of the spring means upon deflection of the springmeans due to engagement of the bearing means with the projectingportions of the spring means upon axial excursion of the spindle. 1.Power driven positioning apparatus with force-dependent shut-off, toposition an engagement member (1) against an abutment (1'') comprising ahousing (15); a spindle (3) passing through the housing and adapted tobe connected to the element to be positioned with predetermined forceagainst the abutment; a motor (6) in driving engagement (4, 5) with thespindle (3), the spindle being subject to axial excursion when theelement impinges on the abutment; bearing means (8, 9) axially spaced onthe spindle and journalling the spindle, the bearing means being axiallymovable with the spindle upon axial excursion thereof; means (10)located in the housing guiding the axial movement of the bearing means;spring means (12, 13, 14) having projecting portions (12, 13) and anattachment portion (14), the projecting portions extending over thebearing means and holding said bearing means between the projectingportions in pre-determined axial position, the attachment portion beingsecured to the housing; and switch means (16, 17) engageable by theprojecting portions of the spring means upon deflection of the springmeans due to engagement of the bearing means with the projectingportions of the spring means upon axial excursion of the spindle. 2.Apparatus according to claim 1, wherein the switch means comprises apair of electrical switches (16, 17) having respective operatingelements (16a, 17a) each, located in the housing for engagement of theoperating elements by the projecting portions of the spring means. 3.Apparatus according to claim 1, wherein the guide means guiding thebearing means are slightly shorter than the distance between theprojecting portions of the spring means.
 4. Apparatus according to claim3, wherein the bearing means comprises stationary and rotary races, andthe spring means locate the stationary races in axial position withrespect to the spindle within the housing.
 5. Apparatus according toclaim 3, wherein the bearing means are ball bearing means and comprisegrooves formed in the spindle, balls running in the grooves, and outerraces carried along in axial direction upon axial excursion of thespindle, and hence the balls in the grooves of the spindle, said outerraces being resiliently compressed against each other by the projectingportions of the spring means.
 6. Apparatus according to claim 1, whereinthe housing comprises a pair of substantially symmetrical shells havinga separating plane passing through the axis of the spindle.
 7. Apparatusaccording to claim 6, wherein the motor has an outer circumferenceform-fitting into the housing.
 8. Apparatus according to claim 1,wherein the spring means comprises a U-shaped leaf spring, theattachment portion forming the base portion of the U-shaped leaf springand being located in engagement with the wall portions of the housing,the projecting portions being formed by the leg portions of the U-shapedleaf spring.
 9. Apparatus according to claim 1, wherein the engagementmeans (1) is non-rotatable and subject to axial travel upon rotation ofthe spindle (3), said engagement element being formed with a racksurface; and a pinion (19) engaging the rack surface.